Summary
- The three-circle symbol seen underneath the Kryptonian World Engine in Man of Steel hinted at Brainiac's involvement in Krypton's technology, teasing the villain's DCEU debut.
- Man of Steel 2 was originally planned to feature Brainiac, but the Man of Steel sequel unfortunately never happened.
- Upcoming DCU titles like Superman: Legacy offer the opportunity for previously overlooked villains like Brainiac to finally take on a main villain role.
Man of Steel hid a DC villain easter egg that may inspire Superman: Legacy to use some scrapped ideas from the canceled Man of Steel 2. Despite his popularity, Henry Cavill's now-retired Superman starred in only one DCEU solo movie, after which he appeared in crossovers and team-ups that featured some of Superman's most famous antagonists. Cavill's Superman faced Zod, Lex Luthor, Batman, and Doomsday during his short-lived DCEU run, but left out many other classic Superman villains who are yet to make the jump from the comic books to the big screen.
A key DCEU sequel almost changed that, as one scrapped Man of Steel 2 script featured Superman fighting Brainiac. Plot details from this script written by Peaky Blinders creator Steven Knight are unknown, but Brainiac's DCEU introduction suggests that Superman's Kryptonian backstory would have been developed further. After all, Brainiac is inherently tied to Krypton's history before its destruction in the source material, and Man of Steel secretly teased the hyper-intelligent villain's influence on General Zod and the invading Kryptonians. Although the DCEU's version of Brainiac may never be shown on screen, Man of Steel's Brainiac easter egg could be revisited by the DCU's upcoming Superman: Legacy.
Brainiac's Emblem Appears in Man of Steel's Final Battle 
When the World Engine charges up during Zod's invasion in Man of Steel's third act, three glowing circles can be spotted beneath. This pattern isn't just the functional design of its lasers, but also a subtle reference to Brainiac's three-circle symbol. The World Engine's shapeshifting, AI-controlled nanobot arms also resemble Brainiac's highly advanced weapons, which suggests that Brainiac played an important role in the creation of Krypton's terraforming machines, and either sold his weapons to Krypton or directly led Krypton's interplanetary conquest efforts prior to Krypton's destruction.
Before Stephen Knight's script for Man of Steel 2 was revealed to feature Brainiac, Man of Steel director Zack Snyder acknowledged his interest in Brainiac as Man of Steel 2’s main villain. Given that Snyder built the foundations for the DCEU with Man of Steel, the three-circle pattern on the Kryptonian World Engine seems more likely to be a deliberate reference to Brainiac, and perhaps even a set-up to Brainiac's main villain role in Man of Steel 2. However, Man of Steel 2 never progressed past the development stage, and Doomsday seems to have been the last DCEU villain directly related to the Kryptonians that Superman faced.
What Superman vs Brainiac In Man of Steel Would Have Looked Like 
Brainiac has often been depicted both as an alien and as a sentient supercomputer. Although the green-skinned Coluan is the most famous version of the villain, the DCEU might have been heading down the evil AI route. Apart from the World Engines' Brainiac symbol and nanotechnology, all the Kryptonian ships in Man of Steel possess an AI system so advanced that Superman is able to talk with a virtual representation of Jor-El as if he were still alive. It would have been easy for Man of Steel 2 to reveal that Brainiac has secretly arrived on Earth as a dormant AI system who's waiting for the right moment to invade.